Crouching behind the Cool Hill (Qingliangshan) in the northwest part of Nanjing, the stone city extends about three thousand meters from the south to the north, with a maximum height of seventeen meters. Built by order of Sun Quan (182-252), the ruler of the Wu Kingdom, it stands on reddish brown rocks on the hill. As it was close to the Yangtze River and built in a strategic place, it was used for naval training by Zhou Yu (175-210), a general of the Wu Kingdom. Zhuge Liang (181-234), the prime minister of the Shu Kingdom, described the terrain of Nanjing as "Zhongshan curling like a dragon and the Stone City crouching like a tiger" when he came to Nanjing on a mission to the Wu Kingdom. Since then, Nanjing has also been referred to as "Stone City." Today, the stone wall is the only attraction left of this once stone city.  (Source: China.org.cn)